Population Pharmacokinetics and Exposure-Response Analyses of Ustekinumab in Patients With Moderately to Severely Active Crohn's Disease.

PURPOSE: Ustekinumab, a fully human immunoglobulin G1κ monoclonal antibody that antagonizes human interleukin-12/23p40, is an effective therapy for several immune-mediated inflammatory diseases, including Crohn's disease (CD). This work characterizes the population pharmacokinetic (PK) and exposure-response (E-R) relationships of ustekinumab in patients with CD using data from four Phase IIb/III clinical studies. METHODS: Serum ustekinumab concentration-time data from 1673 patients after IV and/or SC administration of ustekinumab were fitted simultaneously using nonlinear mixed effects modeling to develop a population PK model, which was subsequently used to evaluate simulation scenarios. Logistic regression E-R models were used to assess relationships between serum ustekinumab concentrations and clinical remission after induction (n = 1910) and maintenance (n = 387) treatment. FINDINGS: Ustekinumab PK properties are well described by a two-compartment model with first-order absorption and elimination. Typical values of PK parameters for a 70-kg patient were: clearance, 0.192 L/d; volume of distribution at steady state, 4.62 L; and intercompartmental clearance, 0.287 L/d. Ustekinumab terminal elimination t1/2 was 19 days, and bioavailability after SC administration was 78.3%. Ustekinumab clearance was not affected by coadministration of immunosuppressive agents or corticosteroids. Body weight, serum albumin, and C-reactive protein (CRP) concentrations, tumor necrosis factor (TNF) antagonist failure status, sex, race (Asian vs non-Asian), and anti-ustekinumab antibody status significantly affected ustekinumab disposition; however, the effects of these covariates on ustekinumab exposure were not clinically relevant. The population PK model predicts that a milligram/kilogram dosing approach will result in lower ustekinumab exposure in patients with lower body weight. A positive E-R relationship was established between ustekinumab concentration and efficacy outcomes. The treatment effect of ustekinumab after induction therapy was more pronounced among patients with higher baseline CRP concentrations relative to those with lower values. IMPLICATIONS: In patients with CD, ustekinumab disposition after IV and SC administration was biexponential and consistent with those in patients with ulcerative colitis. Prior treatment with TNF antagonists or the concomitant use of immunosuppressive agents or corticosteroids had no effect on ustekinumab disposition. None of the covariates that affected ustekinumab clearance had a clinically meaningful impact on ustekinumab exposure. E-R models support recommended posology of ustekinumab in adults with CD; however, an ∼6 mg/kg IV induction dose in pediatric patients with lower body weights may not provide exposure that matches that in adult patients. CLINICALTRIALS: gov identifiers: NCT00771667, NCT01369329, NCT01369342, and NCT01369355.

Making Better Dose Decisions: Using Exposure-Response Modeling to Integrate Efficacy Outcome of Two Phase IIb Clinical Trials of Ubrogepant for Migraine Treatment.

Ubrogepant (MK-1602) is a novel, oral, calcitonin gene-related peptide receptor antagonist in clinical development with positive phase III outcomes for acute treatment of migraine. This paper describes the population exposure-response (E-R) modeling and simulations, which were used to inform the phase III dose-selection rationale, based on ~ 800 participants pooled across two phase IIb randomized dose-finding clinical trials. The E-R model describes the placebo and ubrogepant treatment effects based on migraine pain end points (2-hour pain relief and 2-hour pain freedom) at various dose levels. Sensitivity analyses were conducted to evaluate various assumptions of placebo response in light of the high placebo response observed in one phase II trial. A population pharmacokinetic model describing the effect of formulations was included in the E-R simulation framework to assess potential dose implications of a formulation switch from phase II to phase III. Model-based simulations predict that a dose of 25 mg or higher is likely to achieve significantly better efficacy than placebo with desirable efficacy levels. The understanding of E-R helped support the dose selection for the phase III clinical trials.

Population PK Analyses of Ubrogepant (MK-1602), a CGRP Receptor Antagonist: Enriching In-Clinic Plasma PK Sampling With Outpatient Dried Blood Spot Sampling.

Merck & Co., Inc. (Kenilworth, New Jersey) has recently published an integrated strategy for implementation of dried blood spots (DBS) in late-stage trials for population pharmacokinetic (PK) modeling. We applied this strategy for another late-stage clinical program: ubrogepant (MK-1602), a novel oral calcitonin gene-related peptide receptor antagonist for acute treatment of migraine. At the time of implementation, ubrogepant was entering phase 2 development. DBS was implemented to acquire PK information proximal to an acute migraine event to enable exposure-response modeling. The clinical endpoint was a spontaneous event, which generally occurs outside a clinic visit. Thus, an innovative feature of this trial was facilitating DBS in an outpatient setting. In vitro and bioanalytical tests established initial method feasibility and suitability for further evaluations in the clinic. A quantitative relationship was developed between blood and plasma concentrations from concurrently collected samples in a phase 1 (healthy subjects) and phase 2 (target patient population) study using graphical and population PK approaches. This integrated information was presented to the Food and Drug Administration for regulatory input. Following regulatory concurrence, DBS was poised for use in further clinical studies. Population PK modeling was used to dissect sources of variability contributing to DBS collection in the outpatient setting. What has been learned from this program has informed the broader integrated strategy of Merck & Co., Inc. (Kenilworth, NJ) for DBS implementation in clinical trials and research to improve the precision of PK data collected in an outpatient setting.

A semi-mechanistic model for the effects of a novel glucagon receptor antagonist on glucagon and the interaction between glucose, glucagon, and insulin applied to adaptive phase II design.

A potent novel compound (MK-3577) was developed for the treatment of type 2 diabetes mellitus (T2DM) through blocking the glucagon receptor. A semi-mechanistic model was developed to describe the drug effect on glucagon and the interaction between glucagon, insulin, and glucose in healthy subjects (N = 36) during a glucagon challenge study in which glucagon, octreotide (Sandostatin), and basal insulin were infused for 2 h starting from 3, 12, or 24 h postdose of a single 0-900 mg MK-3577 administration. The drug effect was modeled by using an inhibitory E max model (I max = 0.96 and IC50 = 13.9 nM) to reduce the ability of glucagon to increase the glucose production rate (GPROD). In addition, an E max model (E max = 0.79 and EC50 = 575 nM) to increase glucagon secretion by the drug was used to account for the increased glucagon concentrations prechallenge (via compensatory feedback). The model adequately captured the observed profiles of glucagon, glucose, and insulin pre- and postchallenge. The model was then adapted for the T2DM patient population. A linear model to correlate fasting plasma glucose (FPG) to weighted mean glucose (WMG) was developed and provided robust predictions to assist with the dose adjustment for the interim analysis of a phase IIa study.

Changes in serum creatinine in patients with active rheumatoid arthritis treated with tofacitinib: results from clinical trials.

INTRODUCTION: Small increases in mean serum creatinine (SCr) were observed in studies of rheumatoid arthritis patients during tofacitinib treatment. These SCr changes were investigated and potential mechanisms explored. METHODS: SCr values and renal adverse event data were pooled from five Phase 3 and two long-term extension (LTE) studies. Dose-response relationships and association with inflammation (C-reactive protein (CRP)) were explored using Phase 2 data and confirmed with Phase 3 data. RESULTS: In Phase 3, least squares mean SCr differences from placebo at Month 3 were 0.02 and 0.04 mg/dl for tofacitinib 5 and 10 mg twice daily (BID) (P <0.05), respectively. During Months 0 to 3, confirmed SCr ≥33% increases over baseline were reported in 17 (1.4%; 5 mg BID) and 23 (1.9%; 10 mg BID) patients. Generally, elevations plateaued and remained within normal limits throughout Phase 3 and LTE studies. Exposure-response modeling demonstrated small, reversible effects of tofacitinib on mean SCr, and significant (P <0.05) effects of CRP on model parameters. Phase 3 data confirmed that patients with higher baseline CRP or greater CRP decreases following tofacitinib treatment had the largest increases in SCr. Across Phase 3 and LTE studies, 22 tofacitinib-treated patients had clinical acute renal failure (ARF), predominantly in the setting of concurrent serious illness. CONCLUSIONS: Tofacitinib treatment was associated with small, reversible mean increases in SCr that plateaued early. The mechanism behind these SCr changes remains unknown, but may involve effects of tofacitinib on inflammation. ARF occurred infrequently, was associated with concurrent serious illness, and was unrelated to prior SCr increases.

Population pharmacokinetics of pegaptanib in patients with neovascular, age-related macular degeneration.

The anti-vascular endothelial growth factor (VEGF) aptamer pegaptanib is eliminated primarily by renal clearance. Because renal function declines with age, pegaptanib exposure in patients with age-related macular degeneration (AMD) may increase. Therefore, a population pharmacokinetic (PK) analysis of pegaptanib was undertaken in Western and Asian AMD patients to determine the influence of renal function on apparent pegaptanib clearance (CL). Pegaptanib (0.3-3 mg per eye) was administered every 4 to 6 weeks to 262 AMD patients in 4 studies. Pegaptanib exposures (area under the concentration-time curve [AUC] and maximum plasma concentration) after 8 doses were similar to exposures following the first dose, consistent with the absence of plasma accumulation. A 1-compartment model parameterized in terms of the absorption rate constant, apparent volume of distribution, and CL was used to describe the pegaptanib plasma concentration data. Creatinine clearance (CLCR), body weight (WT), and age influenced pegaptanib PK. Decreasing CLCR from 70 to 30 mL/min doubled AUC. After adjustment for CLCR, WT, and age, the model predicted no race differences in CL or AUC. Given that the therapeutic 0.3 mg per eye dose of pegaptanib results in exposures one-tenth of those observed following the well-tolerated 3-mg dose, these results suggest that no dose adjustment is warranted for AMD patients with moderate renal insufficiency (CLCR >30 mL/min).

Analgesic efficacy of celecoxib in postoperative oral surgery pain: a single-dose, two-center, randomized, double-blind, active- and placebo-controlled study.

BACKGROUND: Celecoxib 200 mg has been reported to reduce pain following dental extraction but to offer poorer pain relief than active comparators. OBJECTIVE: The aim of this study was to compare the efficacy and tolerability of celecoxib 400 mg, the recommended loading dose for treatment of acute pain, with that of ibuprofen 400 mg and placebo following oral surgery. METHODS: This was a single-dose, 2-center, randomized, double-blind, active- and placebo-controlled study in which patients with moderate to severe pain following third molar extraction were randomized to receive a single dose of celecoxib 400 mg, ibuprofen 400 mg, or placebo. Pain assessments were completed using a 4-point pain intensity scale where 0=no pain and 3=severe pain and a 5-point pain relief scale where 0=no pain relief and 4= complete pain relief at baseline and 18 time points over 24 hours. Primary efficacy outcome measures were time to onset of analgesia (the median time to perceptible pain relief in those patients who achieved meaningful pain relief), time-specific pain intensity difference (PID), time-specific pain relief (PR), time-specific sum of PID and PR, and time to use of rescue medication. Times to perceptible and meaningful pain relief (secondary efficacy outcome measures) were recorded using 2 stopwatches. Tolerability was assessed through recording of adverse events, clinical laboratory tests, and physical examinations (including collection of vital signs). RESULTS: One hundred seventy-one patients were randomized to celecoxib 400 mg (30 women and 27 men; mean [SD] age, 21.4 [4.2] years); ibuprofen 400 mg (30 women and 27 men; mean [SD] age, 22.0 [4.7] years); or placebo (34 women and 23 men; mean [SD] age, 21.6 [5.0] years). Mean times to onset of analgesia with celecoxib 400 mg and ibuprofen 400 mg were rapid and comparable (median 28 minutes and 26 minutes, respectively) and were significantly shorter than with placebo (>24 hours) (both, P<0.05 vs placebo). Compared with placebo, mean time-specific PID scores were significantly greater with celecoxib from 0.5 to 24 hours and with ibuprofen from 0.5 to 16 hours (all, P<0.05 vs placebo). Time-specific PR scores with celecoxib and ibuprofen were significantly greater from 0.75 and 0.5 hour, respectively, compared with placebo (all, P<0.05 vs placebo). PID was significantly greater with celecoxib compared with ibuprofen beginning at 11 hours (all, P<0.05). PR scores were significantly higher with celecoxib versus ibuprofen beginning at 9 hours (all, P<0.05). Median (95% CI) time to use of rescue medication with celecoxib (>24 hours) was significantly longer than with ibuprofen (10 hours, 58 minutes [8 hours, 30 minutes- 14 hours, 34 minutes]) or placebo (1 hour, 51 minutes [1 hour, 40 minutes-2 hours, 22 minutes]) (both, P<0.05). The 3 most common adverse events experienced in the celecoxib group were headache (9 [15.8%] patients), nausea (9 [15.8%] patients), and dizziness (6 [10.5%] patients). CONCLUSIONS: In this postsurgical dental pain study, the onset and magnitude of pain relief with celecoxib 400 mg and ibuprofen 400 mg were found to be comparable. In addition, patients who received celecoxib 400 mg as a single dose had a significantly longer time to use of rescue medication and had higher pain relief scores later in the study than those who received ibuprofen 400 mg. Celecoxib was well tolerated compared with placebo.